[Python-checkins] bpo-43822: Prioritize tokenizer errors over custom syntax errors when raising parser exceptions (GH-25866)

[miss-islington]

https://github.com/python/cpython/commit/756b7b9248885d65c2b3b9f1c5a8f66aa2e8de7a
commit: 756b7b9248885d65c2b3b9f1c5a8f66aa2e8de7a
branch: 3.10
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: miss-islington <31488909+miss-islington at users.noreply.github.com>
date: 2021-05-03T18:06:45-07:00
summary:

bpo-43822: Prioritize tokenizer errors over custom syntax errors when raising parser exceptions (GH-25866)

(cherry picked from commit 9142088e7454a392b69a627863b235ecc32aea54)

Co-authored-by: Pablo Galindo <Pablogsal at gmail.com>

files:
A Misc/NEWS.d/next/Core and Builtins/2021-05-04-01-01-04.bpo-43822.9VeCg0.rst
M Lib/test/test_exceptions.py
M Parser/pegen.c

diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index bc0404ea4b04d5..3c427fed561183 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -210,7 +210,7 @@ def testSyntaxErrorOffset(self):
         check('x = "a', 1, 5)
         check('lambda x: x = 2', 1, 1)
         check('f{a + b + c}', 1, 2)
-        check('[file for str(file) in []\n])', 1, 11)
+        check('[file for str(file) in []\n])', 2, 2)
         check('[\nfile\nfor str(file)\nin\n[]\n]', 3, 5)
         check('[file for\n str(file) in []]', 2, 2)
 
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-05-04-01-01-04.bpo-43822.9VeCg0.rst b/Misc/NEWS.d/next/Core and Builtins/2021-05-04-01-01-04.bpo-43822.9VeCg0.rst
new file mode 100644
index 00000000000000..b8815cddf4e2c1
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-05-04-01-01-04.bpo-43822.9VeCg0.rst	
@@ -0,0 +1,2 @@
+The parser will prioritize tokenizer errors over custom syntax errors when
+raising exceptions. Patch by Pablo Galindo.
diff --git a/Parser/pegen.c b/Parser/pegen.c
index e32b2710dbda26..6080cec1489ed8 100644
--- a/Parser/pegen.c
+++ b/Parser/pegen.c
@@ -1283,6 +1283,9 @@ _PyPegen_run_parser(Parser *p)
         reset_parser_state(p);
         _PyPegen_parse(p);
         if (PyErr_Occurred()) {
+            if (PyErr_ExceptionMatches(PyExc_SyntaxError)) {
+                _PyPegen_check_tokenizer_errors(p);
+            }
             return NULL;
         }
         if (p->fill == 0) {